1. Field of Invention
The present invention relates generally to particle removal and air borne molecular contaminant air filters, and, more particularly, to a combination particle and air borne molecular contaminant filter with an activated material separator.
2. Description of Prior Art
Cleanliness of air supplied to clean rooms and other confined environments depends on air filters to remove contaminants in the air. Particle contaminants are typically removed by using air filters with particle removal efficiencies ranging from about 95% to 99.9999+%. A conventional high efficiency particle filter 10, for example, is schematically shown in FIGS. 1a-c. 
High efficiency particle filters 10, such as HEPA or ULPA air filters, are constructed by pleating a continuous sheet of flat filter media 100 into an accordion style construction, as shown in FIGS. 1a-c. 
FIG. 1a is a front view of a particle filter 10, which shows the continuous sheet of flat filter media 100 separated by separators 110 and enclosed within a filter frame 130 on the top, bottom, and left and right sides. The front and back (not shown) sides are open to allow air to pass through the filter 10. FIG. 1a also shows a gasket seal 120 and adhesive bond 140 between the filter media 100/separator 110 and integral filter frame 130.
FIG. 1b is a front expanded view of a portion (portion “A”) of the particle filter 10 as shown in FIG. 1a. 
FIG. 1c is a top expanded view of a portion (portion “B” without the top part of the frame 130) of the particle filter 10 as shown in FIG. 1a. 
The pleating of the filter media 100 allows a large amount of the filter media 100 to be packed into a small geometric shape, increasing surface area and thus the performance of the filter. The pleats are kept apart by separators 110 so that air can freely pass through each pleat without causing the pleats to lose their geometry or spacing, both of which would adversely affect filter 10 performance.
The oldest, and still quite common, method of pleat separation is by means of corrugated sheet separators 110 made from thin gage aluminum, as shown in FIGS. 1a-b. These separators 110 are made as thin as possible to avoid blocking the airflow. In this construction, the corrugated sheet separators 110 not only maintain (keeps intact) the geometry and the structure of the pleated filter media 100, but since the separators 110 are in intimate contact with the air flow, the separators 110 also aid in the optimum distribution of the air throughout the depth of the filter 10.
With the decreasing scale of the tolerable defects and contaminants in processes taking place in a typical clean room and other confined environments, the emphasis is shifting from the filtering of particles to the removal of air borne molecular contaminants (AMC). This is particularly true in the microelectronics, biotechnology, and the newly emerging area of Nano technology and manufacturing, where the dimensions of components and products are approaching molecular sizes. AMCs and other gaseous contaminants are usually removed by passing the air through packed beds of activated materials 200 such as activated charcoal, which is schematically shown in FIG. 2. The activated material 200 is often impregnated with other chemicals to remove specific AMCs such as acids or bases. It is common for the particle and AMC filters to be mounted in series such that the combination of such filters removes both particle and gaseous contaminants. The effectiveness of removal is controlled by the amount of the activated material packed in the box and by the efficiency of the particle filters.
Removal of AMC requires intimate contact between the air stream 210 and the activated material 200, as shown in FIG. 2. In this conventional set-up, which is cumbersome and bulky, a box 20 is filled with the activated material 200. The intricate airflow 210 through the grains of the activated material 200 provides the required intimate contact.
Combination particle and AMC filters are not conventional. For example, in one current attempt to produce such a combination filter, a thin web of fibers made with the activated material was used as a pre-AMC filter to a conventional particle filter set up in series. However, in this case, due to the small quantity of material than can be included in the web of fibers used as the pre-AMC filter, the effectiveness and the life of such webs are poor.